How radiometric dating supports the theory of evolution

The most common rocks observed in this form are sedimentary rocks (derived from what were formerly sediments), and extrusive igneous rocks (e.g., lavas, volcanic ash, and other formerly molten rocks extruded onto the Earth's surface).The layers of rock are known as "strata", and the study of their succession is known as "stratigraphy".Fundamental to stratigraphy are a set of simple principles, based on elementary geometry, empirical observation of the way these rocks are deposited today, and gravity.Most of these principles were formally proposed by Nicolaus Steno (Niels Steensen, Danish), in 1669, although some have an even older heritage that extends as far back as the authors of the Bible.In order for a layer of material to be deposited, something has to be beneath it to support it.It can't float in mid-air, particularly if the material involved is sand, mud, or molten rock.

However, note that because of the "principle of cross-cutting relationships", careful examination of the contact between the cave infill and the surrounding rock will reveal the true relative age relationships, as will the "principle of inclusion" if fragments of the surrounding rock are found within the infill.My thanks to both him and other critics for motivating me.Much of the Earth's geology consists of successional layers of different rock types, piled one on top of another.By dating these surrounding layers, they can figure out the youngest and oldest that the fossil might be; this is known as "bracketing" the age of the sedimentary layer in which the fossils occur.Teach your students about absolute dating: Determining age of rocks and fossils, a classroom activity for grades 9-12.

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